This invention relates to a textile element made of fibres, which contain silicon and a procedure for improving their thermal stability.
Manufacturers of glass fibre and quartz fibre threads, when spinning same, apply a mixture of organic materials, usually called binding agents, to the surface of the thread in order to lubricate the surface and protect the thread from wear by abrasion during the textile process.
However, the maximum possible improvement in resistance to high temperatures is achieved by removing 99% of the binding agent by applying appropriate heat-cleansing techniques. The temperature and duration of the heating will depend on the shape of the textile element and the available equipment, but as a guideline it may be indicated that the textile element will be subjected to a temperature of 400xc2x0 C. for at least 60 seconds.
Depending on the nature of the glass fibre thread, the application of a temperature of over 500xc2x0 C. for periods exceeding 30 seconds can harm the mechanical properties of the textile element.
Textile elements treated with an organic material or with inorganic materials, however, do not improve in thermal stability.
The textile element of the invention made of fibres containing silicon manages to solve the aforesaid disadvantages, while provide other advantages that are described below.
The textile element of the invention made of fibres containing silicon, which is coated with a material, is characterised in that said material is an emulsion of silicone.
Thanks to this characteristic, a textile element of considerable wear resistance is achieved, this resistance being much greater than that of the textile elements treated with an organic material known to date.
Preferably, said fibres include between 40% and 99.9% silicon dioxide.
The silicone emulsion which coats the textile element of the invention is preferably the silicone emulsion marketed under the name of Dow Corning FABRIC COATING 61. This emulsion consists in an anionically stabilised hydroxylated polydiorganosiloxane that contains two hydroxyl groups linked with silicon by molecule and colloidal silica. The emulsion has a pH ranging between 9 and 11.5, while the molecular weight of the polydiorganosiloxane lies between 200,000 and 700,000.
Under a second aspect, the invention relates to a procedure for improving the thermal stability, by increasing considerably the melting point of a textile element made of fibres which contain silicon, which includes the steps of:
impregnation of said textile element with a silicone emulsion; and
curing of the impregnated textile element at a predetermined temperature and for a predetermined time.
Preferably, said procedure also includes a phase of cleaning of the impregnated textile element which is carried out prior to impregnation thereof, this cleaning being implemented at a predetermined temperature and for a predetermined period of time.
According to a preferred embodiment, the emulsion has between 10% and 60% of solid material, while the viscosity is within the range of 10,000 to 30,000 cps. Preferably, the curing of the textile element is carried out at a temperature between 350xc2x0 C. and 90xc2x0 C. for a period of time between 10 seconds and 10 minutes.